TT #246 · Parshas Tazria · Aliyah 7 · Passuk 45
English: As for the person afflicted with tzaraas, his garments shall be torn, his head shall be unkempt, he shall cover his upper lip, and he shall call out, “Impure! Impure!”
Torah Temimah cites Moed Katan 5a for this teaching on the metzora’s public conduct and ritual status.
English: Anyone to whom an affliction occurs, such as a metzora, should inform the public, so that the public will ask for mercy on that person’s behalf.
Textual derivation
The public announcement is not only a warning to keep away; it also informs others of the affliction so they can pray for the person’s recovery.